Kaiserslautern boss Jeff Strasser did not suffer a heart attack during the match against Darmstadt and will undergo further examinations.
The 2. Bundesliga fixture on Wednesday was abandoned at half-time due to a "medical emergency" that led to Strasser being taken to hospital for tests.
Reports in the German media indicated the former Luxembourg international suffered a heart attack, but that was ruled out by Kaiserslautern.
However, Strasser will have further checks on Thursday to try to discover the cause of the problem.
In an update on Strasser's medical condition, a club statement read: "After initial examinations at the hospital in Darmstadt, a heart attack for FCK head coach Jeff Strasser can be ruled out.
"More cardiological examinations will be carried out today [Thursday] to enable a clear diagnosis."
Assistant coach Alexander Bugera will take first-team training in Strasser's absence, with a decision on who will lead the team against Fortuna Dusseldorf on Saturday yet to be decided.